As known, the connecting rods of engines, after moulding, are subjected to a series of rough/finishing chip-forming machinings, most of which are carried out upon the big end and the small end of the connecting rod. These operations can be carried out on machining centers, which typically comprise a motorized machining head which is movable along three axes and is generally provided with a plurality of chucks, e.g., four chucks, in front of which the connecting rods are supported.
During machining, the connecting rods must be locked at specific areas and with calibrated locking forces, which may vary depending on the specific machining to be carried out, both because the positioning/locking mechanisms which engage the connecting rod should not interfere with the machining tool, and because the locking forces, in certain cases, could deform the connecting rod and, consequently, affect the machining accuracy if the deformed area is to be machined.
However, every machining center is provided with a limited number of hydraulic lines and pneumatic lines which can be operated independently from one another in order to control the positioning/locking mechanisms (e.g., eight hydraulic lines and eight pneumatic lines are usually available at most). Therefore, until today, the above-mentioned need for positioning the connecting rods and locking them at different areas and with different forces has prevented from performing all the rough/finishing machinings in a single machining center, and has required to implement lines with a plurality of stations, each of which is specifically equipped for carrying out only one operation (or, at most, a few operations) upon connecting rods of a single type.
As the person skilled in the art will immediately understand, the above circumstance is undesirable. In fact, it would be preferable to have machining centers each having a higher flexibility in relation to the variety of operations which can be carried out and to the different types of connecting rods which can be machined, so that the use of the machining centers can be optimized depending on the production requirements.